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The Fate of the Japanese Submarines which Surrendered in 1945

 The Development of Allied Policy

by Derek Waller

1.   The Potsdam Agreement signed by the British, Americans and Russians on 2 August 1945 sealed the fate of the majority of the Kriegsmarine U-Boats which had surrendered at the end of the European war. The result of the decisions at Potsdam was that 118 U-Boats which had surrendered on either side of the Atlantic were sunk in deep water before 15 February 1946, and that each of the three Allies was allowed to retain only 10 U-Boats for testing and experimental purposes. Additionally, the Potsdam Agreement determined the fate of four of the seven ex-U-Boats which had surrendered under the Japanese flag to the Royal Navy in Singapore and Indonesia in August 1945 at the end of the war in the Far East.

2.   As far as the future of any remaining vessels in the Japanese Navy at the end of the war was concerned, this was covered in outline in the Potsdam Proclamation. This was a statement of the terms for the unconditional surrender of Japan, signed by the President of the United States, the President of the National Government of the Republic of China and the Prime Minister of Great Britain on 26 July 1945. The Proclamation included two important statements affecting the Imperial Japanese Navy (IJN):

“The full application of our military power, backed by our resolve, will mean the inevitable and complete destruction of the Japanese armed forces”.

and

“The Japanese military forces, after being completely disarmed, shall be permitted to return to their homes with the opportunity to lead peaceful and productive lives”.

3.   The diplomatic negotiations at Potsdam did not however specify precisely the fate of the IJN submarines which surrendered, including the two ex-Italian U-Boats that had surrendered in Japan and the ex-U-Boat that had had been gifted to the IJN in 1943.

4.   On the other hand, the United States which was the predominant military power in Japan at the end of the war, was quite clear as to the meaning of the Potsdam Proclamation. Thus, after the Japanese surrender on 15 August 1945, the US Government issued a document “United States Initial Post-Defeat Policy Relating to Japan” (SWNCC 150/4), which was approved by the President on 6 September 1945, and which included the statements that:

“Japan's ground, air and naval forces shall be disarmed and disbanded”.

and

“naval vessels … shall be surrendered and shall be disposed of as required by the Supreme Commander”.

5.   Thus, whilst it was clearly the American intention that all Japanese submarines which had surrendered were to be demolished, scuttled or otherwise destroyed, there had at that time been no specific Allied debates about the detailed arrangements, as had occurred at Potsdam in relation to the surviving German U-Boats.

6.   The purpose of this paper is therefore to outline the diplomatic exchanges between America, Russia and Britain between October and December 1945, which were the prelude to the sinking of all surviving IJN submarines by the US Navy in 1946.

7.   On 17 October 1945, the US Secretary of State, James F Byrnes, wrote to the American Ambassador in Moscow, W Averell Harriman, asking him to:

“Please deliver following message to Mr Molotov: While in London I advised you that the United States Government desired to sink the units of the Japanese fleet which were surrendered to the United States Navy and that I requested that this action be delayed until I could inform you and Mr Bevin of our plan. You did not then present any views.

I am writing now to say that the Navy again has communicated with me, and if you care to express any views with reference to this plan, I should like to hear at an early date so that I can advise the officials of our Navy”.

8.   In response, Ambassador Harriman advised Mr Byrnes on 18 October 1945 that:

“I took the occasion of my call on Molotov today to hand him your personal message regarding sinking of the Japanese Fleet.

Molotov, after reading your message, stated that he would have to study it and consult with his naval authorities before making a reply. He inquired whether it was a question of sinking the entire fleet, both surface and submarine. I told him that I had no further information other than that contained in your message, which I interpreted to indicate the entire fleet”.

9.   A day later, on 19 October 1945, Vyacheslav Molotov, the Russian Minister of Foreign Affairs, replied directly to Mr Byrnes, saying:

“I have received your message regarding the Japanese fleet on October 18.

Having considered the proposal of the Government of the United States regarding the scuttling of the vessels of the Japanese fleet, the Soviet Government is ready to agree that the large vessels of the Japanese navy such as battleships and cruisers as well as Japanese submarines be scuttled”.

10.   On 20 October 1945, Mr Byrnes wrote again to Ambassador Harriman in Moscow, asking him to:

“Please deliver the following message to Molotov: Replying to your message of October 19, I agree to the disposition of the Japanese fleet suggested by you and am advising the foreign ministers of the United Kingdom and China of your suggestions and my agreement with your suggestions”.

11.   This was followed on 26 October 1945 by an internal US State Department memo from Mr J C Vincent, the US Director of the Office of Far Eastern Affairs, to Mr Byrnes, which said:

“This morning I told the Chinese Ambassador Dr Wei and Sir George Sansom of the British Embassy of our decision with regard to the disposition of the remaining vessels of the Japanese Fleet. I said that we had decided to destroy all large vessels of the Japanese Navy, such as battleships and cruisers, as well as Japanese submarines. In imparting this information I made no reference to our discussions of the subject with the Soviet Union.

Neither Dr Wei nor Sir George made any comment other than to say they would notify their Governments”.

12.   The British then entered the debate on 5 December 1945, when the British Ambassador in Washington (Lord Halifax) sent a message to the Mr Byrnes, saying:

“His Majesty’s Ambassador presents his complements to the Secretary of State and has the honour to inform him that Mr Bevin was informed by Mr Byrnes when he was in London that General MacArthur had a Japanese battleship, two Japanese cruisers, and some Japanese submarines which he was proposing to sink. General MacArthur intended to delay a decision as to whether to sink them until the views of His Majesty’s Government in the United Kingdom, the French Government, and the Soviet Government had been obtained.

His Majesty’s Government in the United Kingdom have consulted His Majesty’s Governments in the Dominions and they agree in the following expression of views:

They consider that the United States Government is entitled to determine the policy for the disposal of the Japanese fleet.

They strongly support the proposal to scrap the submarines”.

13.  The final decision that the surviving IJN submarines were to be sunk or scrapped was taken in Moscow on 24 December 1945 at the 11^th (Informal) Meeting of the three Foreign Secretaries (J F Byrnes, V M Molotov and Ernest Bevin). There were no formally agreed Minutes of the Meeting, but the American and British delegations each recorded their own (similar) versions of the proceedings.

14.  The US Delegation’s Minutes of the Meeting record that:

Item 5. Japanese Fleet

“Mr Molotov stated that he wished to discus a further point with regard to Japan. He had exchanged letters with Mr Byrnes with regard to the Japanese fleet. The proposal had been made that the Japanese Fleet by scuttled. He had agreed with this proposal but with certain qualifications [re the smaller vessels].

Mr Byrnes replied that he had accepted Mr Molotov’s proposal and had issued instructions to the navy to fulfill the agreement which they had reached. He did not remember the exact language of the correspondence. However, he had already instructed the US Navy to proceed in accordance with the agreement.

Mr Bevin inquired whether the British Government was a party to this agreement.

Mr Byrnes replied that it was.

Mr Bevin stated that, as he recalled, the British proposal had been that the Japanese naval fleet should be sunk”.

15.  The UK Delegation’s Minutes of the Meeting record that:

Item 5. Japanese Fleet

“Mr Molotov said that he had discussed with Mr Byrnes the question of the Japanese naval and merchant fleets. This was a question which affected Britain and China. He had agreed to the American Government’s proposals subject to certain amendments. The larger naval vessels, and the submarines, were to be scuttled.

Mr Byrnes said that he had not the details of the correspondence with the Soviet Government in mind; but that agreement had been reached on these lines, and he had arranged for instructions to be issued to the navy in accordance with them.

In answer to a question by Mr Bevin he [Mr Byrnes] said that the British Government were parties to this agreement, which had been reached six weeks to two months ago.

Mr Bevin said that Britain had agreed that the bulk of the navy should be sunk.

Mr Byrnes said he regarded the question of the Japanese navy and merchant fleet as settled. He would find out from the United States navy how far they had carried out their programme and let Mr Molotov know”.

16.  Finally, a US Memorandum dated 25 December 1945 recorded details of a further conversation between Mr Molotov and Mr Byrnes at the Moscow Conference of Foreign Ministers:

Item 1.  Disposition of Japanese Naval and Merchant Fleet

“Mr Molotov said that he wanted to talk with the Secretary about the question of the disposition of the Japanese naval and merchant fleet. This question had not been clarified during the discussion yesterday and he wished to find out more about the status of the matter.

The Secretary [Mr Byrnes] replied that he had nothing to add to what he had said and that after an exchange of letters on the subject [in October] he had turned the matter over to the naval authorities and he assumed that it was being carried out. He said that he had had no information since then.

Mr Molotov replied that he had raised the question because the exchange of letters took place over two months ago and he had heard nothing about the matter through any channel.

The Secretary said he would look into the matter upon his return to Washington”.

17.  Subsequently, the US Navy implemented these decisions and, on 26 March 1946, at a Submarine Officers’ Conference in Washington DC (CNO File Ref: Op-414-C31/ss dated 29 March 1946) it was reported that

"Orders are being issued to dispose of all Japanese submarines by sinking. Those in Japan will be sunk at once, those in Pearl Harbour when authorized by SCAP and at the discretion of CinCPAC".

18.   This statement included, by definition, all remaining surviving Japanese submarines, including those which had been incomplete or which has already been decommissioned at the time of their capture, and also including those that had been moved to Pearl Harbour by the US Navy. The submarines in Japan were to be sunk immediately, while the five that had been moved to Pearl Harbour in October 1945 were to be destroyed at the discretion of the C-in-C Pacific Fleet. The decision therefore also included the three ex-U-Boats that had surrendered in Japan, but which had not been destroyed in accordance with the Potsdam Agreement  because the US Navy’s CNO had successfully argued that they were Japanese submarines when they surrendered and therefore outwith the Agreement’s jurisdiction.

19.  At the same time, according to General MacArthur’s Report, a plan was prepared by COMNAVJAP and approved by SCAP on 2 April 1946, which stated that all former Japanese Navy combatant ships larger than destroyer class were to be completely scrapped. It was also planned to sink wrecked and heavily damaged ships in deep water, and to dispose of all submarines afloat.  

20.  Finally General MacArthur’s Report records that, by October 1946, all IJN submarines (a total of 151) had been disposed of. It also quotes from the Tokyo “Pacific Stars and Stripes” newspaper, in which an article dated 4 June 1949 stated that, as at 15 January 1949 - when the whole IJN disposal task was complete:

 “42 submarines had been scrapped and a further 104 had been sunk”.

21.  Thus, in addition to the disposal of the 49 IJN submarines which surrendered, the precise details of which are known, some 100 other submarines were subject to the disposal process; the principle of which had been outlined in the Potsdam Protocol on 26 July 1945, and the details of which had been given political approval on 24 December 1945.

Main Sources:

1.         Butler and Pelly - Documents on British Policy Overseas: Series 1, Volume 2.

2.         Foreign Relations of the United States (FRUS): Diplomatic Papers 1945: Volumes II and VI - available on-line.

3.         The Potsdam Proclamation - available on-line.

4.         US Initial Post-Defeat Policy Relating to Japan (SWNCC 150/4) - available on-line.

5.         General MacArthur’s Report - available on-line.

6.            Submarine Officers’ Conference - Washington DC - 26 March 1946 (CNO File Ref: Op-414-C31/ss dated 29 March 1946) - NARA RG 313. SUBLANT Files. 370/41/12/5-6. Box 8.